Intermittently-fired furnace



Sept. 7 192s. l 1,599,165

H.H.vc:| ARK INTERMITTENTLY FIRED FURNACE Filfed May e, 1922 sept. 741926.` 1,599,165

H. H. CLARK INTERMITTENTLY l FIRED FURNACE Filed May e. 1922 5sheets-sheet 2 Sept. 7,1926. 1 1,599,165

H. H. CLARK INTERMITTENTL'Y FIRED FURNACE Filed May 6. l1922 Y 5Sheets-Sheet 3 @MMM/@wfg Sept; 7 1926.-

' l H. H. CLARK INTERMITTENTLY FIRED FURNACE A Filed May 6. 1922 5Sheets-Sheet 4 l s w Sept. 7 1926. 1,599,165

v H. H. CLARK INTERMITTENTLY FIRED FURNACE Filed May e. 1922 5sheets-sheet 5 Patented-Sept. 7, 192,6..

Homer: H. cLAnx, oF OAK 15mm-ILLINOIS.

INTRMITTENTLY-IRD FURNACE.

Application med May 6,

` chamber which receives thegoo-dsto be heat treated, and, for the sakeof avoiding ill effects of continued combustion during heat treatment,combustion is interrupted and the heating' chamber is purged 'largelyvof products of combustion before each 'charge of goods is introduced,and heat stored in the walls-of the chamber during the interval ofcombustion is given off to the goods durin the interval of heattreatment, andY the reatively immobile and inert furnace atmosphere canbe maintained during the lastnamed intervals.

Eorthe sake of economy in time and heat consumption in the operation ofa furnace of this type,-it isvery desirable to be able to change fromthe heating interval tothe charging interval with the utmostrpromptness, Without residual combustion or unconsumed fuelmixture; alsoto return from the heat treatment interval to the combustion or heatstoring interval with utmost promptness, either as an immediate sequencetothe removal of the charge of goods, or .preferably through automatic'restoration of combustion whenever the temperature of the chamber fallsto apredetermined degree, and provided the charge of goods is absent-from the heating chamber; and one object ofthe present inventionisftopro'vidve 'firing apparatus which willinsure these conditions y inthe furnace operation.

Accordingly, one feature of the present invention consistsin providing alfurnace of v the class, described with burners adapted to supply fuelin Huid form along with an oxidizing agent, in such close proportions aswill insure complete combustion, together with means for initiating andarresting the fiow of fuel mixture through the burners instantly astheconditions demand;v means being provided for.` coordinating the fuel,

controlling meansl and the flue controlling damper of the furnace in amanner to open the latter simultaneously with the initiationofcombustion, and to close the same as combustion is arrested'. Afeature incident to the'preferred embodiment of this part of the 1922.SerialV No. 559,108..

invention consists in utilizing burners of suchcharacter thatimmediately the flow of fuel is arrested, `residual fuel V,Within theburner will be at once consumed, as, for instance, by'so-called backfiring, so that there iis no residual combustion taking place in thechamber, and the latter can bev opened immediately Afor purging andintroduction ofthe goods. Another feature incident to 4the preferredembodiment of this part of the invention consists in the provision ofcombustion chambers between the discharge ends of the burners and theheating chamber so that ignition and oxidation are practically completebeforethe gases leave the combustion chambers, and products ofcombustion alone circulate inthe heating chamber. Another object of thepresent invention is to insure prompt and uniform distribution of heatthroughout the Walls of the heating chamber; and to this.end, anotherfeature of 4the invention consists in arranging the burners as aplurality of units Adistributed along the sides of the furnace anddischarging their-products of combustion across the bottom of theheating chamber through tunnels constructed transversely of the piersthat support the goods, and into impingement against the Walls of thechamber opposite the burner; the burners on o posite sides of thefurnace and the tunnels through Which they discharge, being alternatedin `position so that a burner on one side discharges its hotgasesbetween the lines of two opposite burners, and the gases are thusdistributed uniformly an-d in rising columns -J nlp along the oppositeinner'walls of the cf1 amber and across the roof to the escape Anotherobject of the present invention is to so construct the inner Walls ofthe heating chamber in an intermittently fired furnace, that the areathrough which the walls alternately absorb and radiate heat will begreatly enlarged in proportion to the caacity of the heating chamber.Accordingy, another feature of the present invention consists inconstructing the inner Wall of the 4heating chamberwith recesses,pockets,

grooves, cliannel's, or the like, all With an internal chamber thatdevelops inner superficial heat absorbing areas-communicating with .theheating chamber through the medium of such recesses, apertures, or thelike,

chamber through means of recesses,

vfuel and simultaneously actuating -the flue damper, controlling thecircuits of this motor by a limiting pyrometer, and introducing into thecontrolling circuit a circuit closer that is responsive to the presence,on

\the outside of the furnace, of :track-bar or other means through whichthe goods are conveyed into and out of the furnace.

In order that the invention may be fully understood, the preferredembodiment of the several features thereof is shown in the accompanyingdrawings, in which Figure y1 is a side elevation of a furnace equippedwith certain of the 'features of the invention.

Figure 2 is a front elevation of the same.

Figure 3 is a horizontal section of the same on the line 3X-3X ofFigures 1 and 2.

Figure 4 is a vertical transverse section on the line 4X X of Fi ures 1and 3.

Figures 5, 6, and are detail perspective views showing dierentconstructions of channelled, grooved, or recessed inner walls of aheating chamber.

Figures 8 and 9 are fragmentary views showing, respectively, in verticaltransverse section and in elevation, a construction of false inner walladapted to develop with the main inner wall of the heating chamber aninterior space connected with the heating apertures, or the like, inorder to still further enlarge the heat-absorbing areas.

Figure 10 is a schematic view showing an electrical installationsuitable for controlling the combustion by a pyrometer, and subjectingsuch control to the location of the vehicle which accompanies the goodsinto and out of the heating chamber.

Figure 11 is a detail view of a circuit closing switch suitable for usein the installation illustrated in Figure 10.

1 represents a furnace, which may be of known construction, 2 the doorthereof, and 3 counterbalances .controlling the door through the mediumof flexible connectors 4 passing over pulleys 5. 6 represents a damperadapted to control the'escape flue 6a which communicates with the uptake6b through which products of combustion escape; and this damper 6 is ooitrolled by flexible connector 7 passing over pulley 8 to acounterbalance 9. 10 represents burners introduced horizontally throughthe sides of the furnace at a level slightly above the bottom of theheating chamber, as hereinafter explained, and in 'such positions on theopposite sides of the furnace that the burners on one side alternate thelines of their discharge with the burners on the other side. Each burner10 is provided with a known construction of fuel mixing attachment 11which has 'the function of intermingling with the gaseous fuel withsubstantial exactness thel quantity of oxidizing medium (in the presentinstance air) required for complete oxidation of the fuel, so thatignition can be renderedI substan tially complete within a very shortdistance of the end of the -burner and substantially before the gasesenter the heatin chamber, as,y hereinafter explained. Each uelconditioning device .11 is supplied with fuel through a branch pipe l2leading from a. gas main 13; and each branch pipe 12 has a controllingvalve 14 through means of which to regulate the fuel apportioned to,

the respective burners, and closing the supply main 13, and throughtality, the burners may so that by opening of fuel through the a singleinstrumenbe collectively controlled, and each will perform in exact ac-'cordanee with its individual adjustment.

The burners collectively will thus insure proper distribution of heatunits throughout the heating chamber.

As will be'seen upon reference to Figure 2,- the mains 13 on the resective sides of the furnace, are connected t rough a crossover pipe 13so that a single fuel control may serve for both groups of burners. As ameans for supplying and arrestin fuel in the main'l, a valve 15 isemployed, and this valve is controlled in common with the damper 6through theYI medium of an arm 16 which is connected with,the sheave 8at 17, and with the valve 15 through the medium of an arm 18. l19represents a connecting element intended to lead to any point of controlwhich may be manual, as when the operatives watch a reading pyrometerand turn on and off the gas at the proper interquence of the presence ofhot surfaces with which the fuel. mixture contacts, as hereinafterdescribed.

Referring to the automatic pyrometer control for the valve 15 and damper6, as shown in Figure 10, 20 'represents a lever pivoted at 21,vconnected atone end Ito the rod 19 and at its other endto a rack-bar 22which receives the pinion 23 of a reversible v electric motor 24.25`frepresents a pyrometer that current is supplied to the motor in onedirection or the other as the arm 26 reaches.

a contact, and according V- to the particular contact which it reaches.To render the circuit 31, 31a inoperative so long as goods are in theheating chamber of furnace 1, the con ductors of said circuit are soinvolved with the circuit closer 34, lying in the path of the7 rack-bars35 which serve as a vehicle for the introduction of .he goods intotheffurnace, that so long as the rack-bars are in the furnace, whithertheyare introduced by the conventional charging fork 36 pivotallymounted on truck wheels 37, the circuit closer 34 will be open and motor24 cannot act to shift the lever 19 of the heating apparatus. Butwhenever the rack-bars 35. are out of the furnace and resting upon thecircuit closers 34, the circuit; 31, 31a will be operative to energizethe motor 24 whenever the thermo-couple 29 moves the contact -26 toeither of the terminals 27, 28.

suitable Iconstruction Y may be ern-y An ployed' for kthe circuit closer34. According to Figure 11, this mayv consist of a framelike member 34pivoted at 38, held normally elevated by spring 39 to a plane above thatto which it will be depressed by the rack- Irack-bars rest upon bars 35,and having resilient terminal 31x depressed upon contact 315' wheneverthe the frame 34.

In order to control combustion and insure ignition upon release of fuelmixture from the burners 10, and discharge the gases into the heatingchamber as completely oxidized products of combustion, combustion cham-`bers 40 are arranged between the discharge ends of the-burners 1() andthe heating cham' These combustion chambers consist of .thimbles or ueliners of highly refractory material adapted to store sutiicient heatfromoneperiod Ofcombustion to ignite the fuel mixture when it isreleased for an ensuing tion. In alignment with each combustion chamber40 is a tunnel 42 formed through a `series of piers 43 upon which therack-bars 35 rest while supporting the goods within the chamber 41, andthese tunnels extend nreferablv to the opposite wall of the heatlperiodof coinbus-l `tured, as, for instance,

ing chamber, tunnels as already described being located on alternatinglines so that the main body of hot gas or products of combustion fromeach burner passes across the opposite Wall and arises thence in closeimpingement against the Walls and against the roof of the chamber untilit escapes throughthe uptake 6b into the flue 6a and past the damper 6,as alreadydescribed. Of course, appreciable portions of the hot gases byreason of their expansion will rise between the piers and circulate inthe main space of the chamber 41, but the directing andimpinging actionof the burners described will insure high efficiency vin heattransferring contact bet-ween the gases and the walls of the chamber. v

In order to enlarge the absorption capacity of the wallsl of the chamber41,;they are, as already stated, provided with some form ofchannel,groove, recess, pocket, or

the burners and their aligned i the like which greatly `increases thesupericial heat absorbing area. One form of wall construction havingthis result is shown in Figure 5, wherein 44 represents vertical ribs orpilastersl merged into sealing ribs or archesrand develop between themvertical flue like channels 45 tluough which the gases will iow inreaching the uptake 6". These structural members 44l obviously increasethe superficialV heat absorbing area of the heating chamber walls to anextent represented by their dimension perpendicular to the wall,multiplied by their total length,`

which obviously will provide a very substantial increment in the heatabsorbing surface,

According to Figure 6, horizontal ribs or ledges 44 are provided ina'manner to form horizontal grooves 45 l which' will vtrap the upwardlyflowing impinging sheet of gases, andv by eddy currents causeimpingement` thereof against the increased superficial areas provided.

According to Figure 7, the protruding( portions of the wall are in theform of limited-rectangular members 44b in the nature pf checker-work,leaving segregated pockets 45" among them in a' manner to affordanincrement of superficial area at least c ual to that attained bytheconstructions of ig-v ures 5 and 6. 1

When it is desired to get a very largel in' crease in heatabsorbing andradiating surface, as, is used for heating bodies of relatively largemass, for instance,- in the enameling of bath tubs, and the heatinginterval has to be continued for a proportionately longer time, I preferto employ a lining or falsewall 46 in4 the chamber 41, with its arealargely aperby lopenings 47,

for instance, where the. furnace` thereby providing a recess 4 8, thewa-lls of f surfaces, impingeme'nt against which byllthe and leave a-free opening for the inrush of hot gases is induced by thecommunication cold air between the closer, the motor circuit 31, 31a

' minal 28, motor 24 will be actuated in the dithrough the the charge offinished 4 moved and the circuit of the burners, and the main door 2closed.

at proper y on the part -matically ensue.

piers 43 and the upof the recess 48 with the escape Hue 6, 6b. warddisplacement and outHow of products of The liner or false wall 46 may beconstructed combustion. Cutting off of the fuel mixture of frame-liketile, such, for instance, as ythe in the burners 10 results in immediatearrest tile commonly used to build mutlles in'enamof combustion becauseoxidation is practieling or annealing furnaces, but with the callycomplete before the mixture leaves the thin panels of such tilewholly-removed in combustion chambers 40. Re-ignition, howorder toprovide the openings 47. 't ever, will take place immediately upon res-In the operation of thetfurnace, thevalve torat-ion of the flow of'fuelmixture because 15 and the damper 6 will be iirst opened by of the heatstored up in the refractory liners hand, fuel mixture ignited at one ormore 40. Even the fuel mixture contained in the conditioning devices 11will be consumed at `the interruption of fuel supply, because themixture is combustible at. the upper ends of bustion chambers 40` untilthe inner Walls of these devices and back firing will result as thefurnace have absorbed sufficient temperasoon as the momentum of fuelmixture is ture, Whenvthe furnace can be left to autoarrested.A f maticheat control, which will shut the valve I claim: t 15 and damper 6. Thegoods are arranged l. furnace for subjecting materials to upon therack-bars 35 (Figure 10), the furheat underinert environment, comprisinga nace door 2 is opened, the rack-bars contain- Closed chamber in whichthe materials are ing the goods are introduced through means heated, aplurality of fuel burners havin of conventional fork 36, .the fork iswithi air-tight connection with and delivering drawn, and the door 2 isclosed. The goods products of combustion into said chamber, will bepermitted to remain for a time inand a master control for all of saidburners terval predetermined by experience, when adapted to completelyarrest and re-establish the door 2 is opened and the goods drawn. Assoonas one or more of the 35 rest upon the frame 34 lof the circuit toire-ignite fuel When restored thereto.

Will be closed 2. In an intermittently Hred furnace for so that if thearm 26 of the pyrometer 25 has subjecting ,materials to heat under inertenin the meantime moved into contact with tervironrnent, a plurality ofburners, a closed heating chamber with which said burners rection toopen thek valve 15 and Hue 6 and have air-tight connection, connectionsfor restore combustion: Under ordinary condisupplying said burners witha mixture of tions, with theeiciency of the burner and fuel andoxidizing medium for said fuel, hot gas distribution herein described,temsaid burners having ignition combustion perature -will be restoredand arm 26 will chambers which deliver products of coinmoveto contact'`27 and close the circuit bustion to said furnace; and a furnace tem-`motor 24 in the direction to ar-v perature actuated single mastercontrol rest the fuel and close the damper 6 while adapted to completelyarrest and release goods isV being refuel to said burners.' movedl fromthe rack-bars 35 and a new 3. ln an intermittently fired furnace forcharge of goods to be baked arranged theresubjecting materials to heatunder inert enon. In thls way' the vfurnace will 4be kept .vironment aclosed heating chamber, a plutemperature without attention rality ofburners Htted air tight into the of the operatives. wall of `the furnaceand having ignition chambers adapted to ignite fuel delivered If at anytime the goods should'be left 1n the furnace until the temperature.drops thereto and through which the respective burners deliver into theinterior of the heatbelow the point` developing contact between arm 26and low temperature terminal 28, the ling chamber, means for deliveringfuel to lgnition cannot be restored because of the the burners, meansfor automatically mixa sence of the rack-bar 35 over the circuit ing airwith the fuel so delivered, in adv closer 34; but as soon Combustionwill then proceed at allthe burners and will restrict itself to the comvcloserv 34is depressed bers, a furnace-temperatu'rev actuated master bythe presence of a rack-bar thereon, restovfuel supply valve opening -andclosing to ration of furnacetemperature willauto- Supply and' completelyinterrupt How of fuel, a Hue cutoff, and means connecting said Huecutoff and fuel supply valve to enforce opening and closing of the samein `\unison. v

4. In an intermittently fired furnace for Scavenging orr purgingtheheating chamber 41 of products of combustion results automaticallyfromraising of the door 2 which, as suggested by the dotted outline ofthe heating chamber in Figure '-2, will arise subjecting materials toheat under inert enas the goods are revVance of its discharge intortheignition chamabove the crest of the crown of the arch vironment, aplurality of fuel burners having ignition chambers with which saidburners have air tight connection and through which they deliver burninggases, enclosed heating chamber receiving said gases from said ignitionchambers, and a master fuel sup ly control for all of said burnersadapte' to com letely arrest and restore su ply of fuel t creto; saidignition cham ers being constructed with ignition liners that store heatabove the ignition point of the fuel and cause re-ignition of the mastercontrol.

y 5. In a furnace .for subjecting materials to heat under inertenvironment, a heating chamber, a fuel supply for said heating chamber,an electric motor adapted to control said fuel supply, circuits for saidmotor, a yrometer controlling said circuits, meansor charging materialsto be treated,

into the furnace, and a circuit closer also controlling said circuitsand which is in turn controlled by the' furnace charging means.

6. In a heat treating furnace, furnace charging means adapted to assumepositions eithervvithin or out of the furnace, burners for heating saidfurnace, means controlling thev operation of said burners and meanswhereby the control. of the burners is made dependent upon the positionof the furnace -charging means. fuel. when restored to the burners 'bythe 7,. In an intermittently operated furnace for subjecting materialsto heat under inert enviroment, burners for heating the furnace,

fuel delivery controlling-means for said burners, and meanswhereby said.controlling means is rendered ineffective to deliver fuel While acharge ofmaterial is in the furnace.

Signed at Chicago, Illinois, this 29th day 40 of April, 1922.

HORACE H. CLARK.

